[tex]\bf \stackrel{f(x)}{y}=1-x-x^2\implies y=-x^2-x+1
\\\\\\
\textit{ vertex of a vertical parabola, using coefficients}\\\\
\begin{array}{lccclll}
y = &{{ -1}}x^2&{{ -1}}x&{{ +1}}\\
&\uparrow &\uparrow &\uparrow \\
&a&b&c
\end{array}\qquad
\left(-\cfrac{{{ b}}}{2{{ a}}}\quad ,\quad {{ c}}-\cfrac{{{ b}}^2}{4{{ a}}}\right)
\\\\\\
\left(-\cfrac{{{ b}}}{2{{ a}}}\quad ,\quad \stackrel{maximum}{1-\cfrac{(-1)^2}{4(-1)}}\right)[/tex]
